.public-nav{
    display: -webkit-box;
    display: -moz-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-pack: justify;
       -moz-box-pack: justify;
        -ms-flex-pack: justify;
            justify-content: space-between;
    position: fixed;
    z-index: 1;
    bottom: 0;
        left: 0;
    width: 100%;
    background-color: #f8f8f8;
    text-align: center;
        border-top: 1px solid #b2b2b2;
}
.public-nav li span {
    display: block;
    margin-bottom: 6px;
    line-height: 1.5;

}
.public-nav li.active span {
    color: #DC3023;
}

.public-nav li {
    width: 25%;

}
.public-nav li a{
        display: inline-block;
        width: 100%;
        height: 100%;
        font-size: 24px;
        color: #333;
        -webkit-box-sizing: border-box;
        -moz-box-sizing: border-box;
        box-sizing: border-box;
}

.public-nav li a img{
    margin-top: 8px;
    height:18px;
    /* margin-bottom: 8px; */
}


 /* 400 以下   400  -  480 一档  480 以上的是一档  */
 @media screen and (max-width:399px) {
    .public-nav li a img{
        height: 28px;
        /* margin-bottom: 6px; */
    }
    .public-nav li a{
        font-size: 12px;
    }
 }
 @media (min-width: 400px) and (max-width: 480px) {
    .public-nav li a img{
        height: 34px;
        /* margin-bottom: 8px; */
    }
    .public-nav li a{
        font-size: 14px;
    }
 }
 @media screen and (min-width: 481px) {
    .public-nav li a img{
        height:40px;
        margin-bottom: 12px;
    }
    .public-nav li a{
        font-size: 25px;    /* 最大档 */
    }
 }